.\"-
.\" Copyright (c) 1997 Søren Schmidt
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.Dd February 25, 2012
.Dt VGL 3
.Os
.Sh NAME
.Nm VGLBitmapAllocateBits ,
.Nm VGLBitmapCopy ,
.Nm VGLBitmapCreate ,
.Nm VGLBitmapDestroy ,
.Nm VGLBitmapPutChar ,
.Nm VGLBitmapString ,
.Nm VGLBlankDisplay ,
.Nm VGLBox ,
.Nm VGLCheckSwitch ,
.Nm VGLClear ,
.Nm VGLEllipse ,
.Nm VGLEnd ,
.Nm VGLFilledBox ,
.Nm VGLFilledEllipse ,
.Nm VGLGetXY ,
.Nm VGLInit ,
.Nm VGLLine ,
.Nm VGLKeyboardInit ,
.Nm VGLKeyboardEnd ,
.Nm VGLKeyboardGetCh ,
.Nm VGLMouseInit ,
.Nm VGLMouseMode ,
.Nm VGLMouseSetImage ,
.Nm VGLMouseSetStdImage ,
.Nm VGLMouseStatus ,
.Nm VGLPanScreen ,
.Nm VGLSetBorder ,
.Nm VGLSetPalette ,
.Nm VGLSetPaletteIndex ,
.Nm VGLSetVScreenSize ,
.Nm VGLSetXY ,
.Nm VGLTextSetFontFile
.Nd Video Graphics Library functions
.Sh LIBRARY
.Lb libvgl
.Sh SYNOPSIS
.In sys/fbio.h
.In sys/consio.h
.In sys/kbio.h
.In vgl.h
.Ft int
.Fn VGLInit "int mode"
.Ft void
.Fn VGLEnd "void"
.Ft void
.Fn VGLCheckSwitch "void"
.Ft int
.Fn VGLTextSetFontFile "char *filename"
.Ft int
.Fn VGLKeyboardInit "int code"
.Ft void
.Fn VGLKeyboardEnd "void"
.Ft int
.Fn VGLKeyboardGetCh "void"
.Ft int
.Fn VGLMouseInit "int mode"
.Ft void
.Fn VGLMouseMode "int mode"
.Ft int
.Fn VGLMouseStatus "int *x" "int *y" "char *buttons"
.Ft void
.Fn VGLMouseSetImage "VGLBitmap *AndMask" "VGLBitmap *OrMask"
.Ft void
.Fn VGLMouseSetStdImage "void"
.Ft u_long
.Fn VGLGetXY "VGLBitmap *object" "int x" "int y"
.Ft void
.Fn VGLSetXY "VGLBitmap *object" "int x" "int y" "u_long color"
.Ft void
.Fn VGLLine "VGLBitmap *object" "int x1" "int y1" "int x2" "int y2" "u_long color"
.Ft void
.Fn VGLBox "VGLBitmap *object" "int x1" "int y1" "int x2" "int y2" "u_long color"
.Ft void
.Fn VGLFilledBox "VGLBitmap *object" "int x1" "int y1" "int x2" "int y2" "u_long color"
.Ft void
.Fn VGLEllipse "VGLBitmap *object" "int xc" "int yc" "int a" "int b" "u_long color"
.Ft void
.Fn VGLFilledEllipse "VGLBitmap *object" "int xc" "int yc" "int a" "int b" "u_long color"
.Ft VGLBitmap *
.Fn VGLBitmapCreate "int type" "int xsize" "int ysize" "byte *bits"
.Ft void
.Fn VGLBitmapDestroy "VGLBitmap *object"
.Ft int
.Fn VGLBitmapAllocateBits "VGLBitmap *object"
.Ft int
.Fn VGLBitmapCopy "VGLBitmap *src" "int srcx" "int srcy" "VGLBitmap *dst" "int dstx" "int dsty" "int width" "int hight"
.Ft void
.Fn VGLBitmapPutChar "VGLBitmap *Object" "int x" "int y" "byte ch" "u_long fgcol" "u_long bgcol" "int fill" "int dir"
.Ft void
.Fn VGLBitmapString "VGLBitmap *Object" "int x" "int y" "char *str" "u_long fgcol" "u_long bgcol" "int fill" "int dir"
.Ft void
.Fn VGLClear "VGLBitmap *object" "u_long color"
.Ft void
.Fn VGLSetPalette "byte *red" "byte *green" "byte *blue"
.Ft void
.Fn VGLSetPaletteIndex "byte color" "byte red" "byte green" "byte blue"
.Ft void
.Fn VGLSetBorder "byte color"
.Ft int
.Fn VGLSetVScreenSize "VGLBitmap *object" "int vxsize" "int vysize"
.Ft int
.Fn VGLPanScreen "VGLBitmap *object" "int x" "int y"
.Ft void
.Fn VGLBlankDisplay "int blank"
.Sh DESCRIPTION
.Nm Libvgl
is a library that enables the programmer access to the graphics
modes supported by the console driver (syscons).
The library takes care of
programming the actual video hardware, and provides a number of simple
functions to do various graphic operations.
There is also support for a
mouse via the standard mouse system in
.Fx ,
see
.Xr mouse 4 ,
including the ability to transparently have a mouse pointer superimposed on
the graphic image currently being worked on.
The library takes care of screen switching by storing the current image in
memory before switching to another virtual console, and restoring when the
user switches back.
This allows several graphic applications at once, but
on different virtual consoles.
.Pp
Below is a short description of the various functions:
.Pp
.Fn VGLInit
initialize the library and set up the graphic mode
.Va mode .
.Pp
.Fn VGLEnd
terminate graphic mode, and restore the screenmode that was active before
.Fn VGLInit
was called.
.Pp
.Fn VGLCheckSwitch
if the program goes into longer periods of processing without doing
any graphics output, calling this function occasionally will allow
the system to switch screens.
.Pp
.Fn VGLTextSetFontFile
instruct the char/string functions to use the font in file
.Pa filename
instead of the builtin font.
.Pp
.Fn VGLKeyboardInit
set up the keyboard in the
.Dq raw
I/O mode and
specify the key code to be used.
.Va code
must be
.Dv VGL_XLATEKEYS ,
.Dv VGL_CODEKEYS ,
or
.Dv VGL_RAWKEYS .
When
.Dv VGL_XLATEKEYS
is specified, the keyboard translates the raw keyboard scan code into
a character code.
If
.Dv VGL_RAWKEYS
is used, the raw keyboard scan code is read as is.
.Dv VGL_CODEKEYS
is the intermediate key code; each key is assigned a unique code whereas
more than one raw scan code may be generated when a key is pressed.
.Pp
.Fn VGLKeyboardEnd
when you have finished using the keyboard, call this function.
.Pp
.Fn VGLKeyboardGetCh
read one byte from the keyboard.
As the keyboard I/O is in the
.Dq raw
input mode, the function will not block even if there is no input data,
and returns 0.
.Pp
.Fn VGLMouseInit
initialize the mouse.
The optional on-screen mouse pointer is shown if the
argument is
.Dv VGL_MOUSESHOW .
.Pp
.Fn VGLMouseMode
either shows the mouse pointer if the argument is
.Dv VGL_MOUSESHOW ,
or hides the mouse pointer if the argument is
.Dv VGL_MOUSEHIDE .
.Pp
.Fn VGLMouseStatus
returns the current mouse pointer coordinates and button state in
.Va x , y ,
buttons.
The return value reflects if the mouse pointer
is currently shown on screen or not.
.Pp
.Fn VGLMouseSetImage
with this function it is possible to change the image of the mouse pointer
on screen.
.Pp
.Fn VGLMouseSetStdImage
this function restores the mouse pointer to the standard arrow.
.Pp
.Fn VGLGetXY
retrieves the color of the pixel located at
.Va x , y ,
coordinates of the
.Va object
argument, and returns it as a u_long value.
.Pp
.Fn VGLSetXY
sets the color of the pixel located at
.Va x , y ,
coordinates of the
.Va object
argument to
.Va color
u_long value.
.Pp
.Fn VGLLine
draw a line from
.Va x1 , y1
to
.Va x2 , y2
in color
.Va color .
.Pp
.Fn VGLBox
draw a box with upper left hand corner at
.Va x1 , y1
and lower right hand corner at
.Va x2 , y2
in color
.Va color .
.Pp
.Fn VGLFilledBox
draw a filled (solid) box with upper left hand corner at
.Va x1 , y1
and lower right hand corner at
.Va x2 , y2
in color
.Va color .
.Pp
.Fn VGLEllipse
draw an ellipse centered at
.Va xc , yc
make it
.Va a
pixels wide, and
.Va b
pixels high in color
.Va color .
.Pp
.Fn VGLFilledEllipse
draw a filled (solid) ellipse centered at
.Va xc , yc
make it
.Va a
pixels wide, and
.Va b
pixels high in color
.Va color .
.Pp
.Fn VGLBitmapCreate
create a bitmap object and initialize it with the specified
values and bit data.
.Va type
must be
.Dv MEMBUF
for the in-memory bitmap.
.Va bits
may be NULL so that bitmap data may be associated later.
.Pp
There also is a macro,
.Fn VGLBITMAP_INITIALIZER "type" "xsize" "ysize" "bits"
to initialize a statically declared bitmap object.
.Pp
.Fn VGLBitmapDestroy
free the bitmap data and the bitmap object.
.Pp
.Fn VGLBitmapAllocateBits
allocate a bit data buffer for the specified object.
.Pp
.Fn VGLBitmapCopy
copy a rectangle of pixels from bitmap
.Va src
upper left hand corner at
.Va srcx , srcy
to bitmap
.Va dst
at
.Va dstx , dsty
of the size
.Va width , height .
.Pp
.Fn VGLBitmapPutChar
write the character
.Va ch
at position
.Va x , y
in foreground color
.Va fgcol .
If
.Va fill
is != 0, use the color
.Va bgcol
as background otherwise the background is transparent.
The character is drawn in the direction specified by the argument
.Va dir .
.Pp
.Fn VGLBitmapString
write the string
.Va str
at position
.Va x , y
in foreground color
.Va fgcol .
If
.Va fill
is != 0, use the color
.Va bgcol
as background otherwise the background is transparent.
The string is drawn in the direction specified by the argument
.Va dir .
.Pp
.Fn VGLClear
clears the entire bitmap to color
.Va color .
.Pp
.Fn VGLSetPalette
this function sets the palette used, the arguments
.Va red , green , blue
should point to byte arrays of 256 positions each.
.Pp
.Fn VGLSetPaletteIndex
set the palette index
.Va color
to the specified RGB value.
.Pp
.Fn VGLSetBorder
set the border color to color
.Va color .
.Pp
.Fn VGLSetVScreenSize
change the virtual screen size of the display.
Note that this
function must be called when our vty is in the foreground.
And
.Va object
must be
.Va VGLDisplay .
Passing an in-memory bitmap to this function results in error.
.Pp
The desired virtual screen width may not be achievable because
of the video card hardware.
In such case the video driver (and
underlying video BIOS) may choose the next largest values.
Always examine
.Va object->VXsize
and
.Va VYsize
after calling this function, in order to see how the virtual screen
is actually set up.
.Pp
In order to set up the largest possible virtual screen, you may
call this function with arbitrary large values.
.Pp
.Dl VGLSetVScreenSize(10000, 10000);
.Pp
.Fn VGLPanScreen
change the origin of the displayed screen in the virtual screen.
Note that this function must be called when our vty is in the
foreground.
.Va object
must be
.Va VGLDisplay .
Passing an in-memory bitmap to this function results in error.
.Pp
.Fn VGLBlankDisplay
blank the display if the argument
.Va blank
\*(Ne 0.
This can be done to shut off the screen during display updates that
the user should first see when it is done.
.Ss Program termination and signal processing
It is important to call
.Fn VGLEnd
before terminating the program.
Care must be taken if you install signal handlers and try to call
.Fn VGLEnd
and
.Xr exit 3
to end the program.
If a signal is caught while the program is inside
.Nm libvgl
functions,
.Fn VGLEnd
may not be able to properly restore the graphics hardware.
.Pp
The recommended way to handle signals and program termination is to
have a flag to indicate signal's delivery.
Your signal handlers set this flag but do not terminate
the program immediately.
The main part of the program checks the flag to see if it is
supposed to terminate, and calls
.Fn VGLEnd
and
.Xr exit 3
if the flag is set.
.Pp
Note that
.Fn VGLInit
installs its internal signal handlers for
.Dv SIGINT , SIGTERM , SIGSEGV ,
and
.Dv SIGBUS ,
and terminates the program at appropriate time,
after one of these signals is caught.
If you want to have your own signal handlers for these signals,
install handlers
.Em after
.Fn VGLInit .
.Pp
.Dv SIGUSR1
and
.Dv SIGUSR2
are internally used by
.Nm libvgl
to control screen switching and the mouse pointer,
and are not available to
.Nm libvgl
client programs.
.Sh HISTORY
The
.Nm vgl
library appeared in
.Fx 3.0 .
.Sh AUTHORS
.An S\(/oren Schmidt Aq Mt sos@FreeBSD.org
